Carbon dioxide is an inexhaustible inexpensive chemical raw material, and it has been recently noted to fix carbon dioxide into a chemical material on a large scale. Since Inoue et. al. synthesized aliphatic polycarbonates having high molecular weight by using the copolymerization of carbon dioxide and an epoxy compound in 1969, the study on the copolymerization of carbon dioxide and epoxy compounds has been continuously deepened and developed. Furthermore, it is a research focus in the field of polymer sciences to synthesize polymer materials by using carbon dioxide as the raw material. Poly(propylene carbonate) (PPC) is an alternating copolymer of carbon dioxide and propylene oxide, which belongs to the biodegradable environment-friendly materials.
At present, poly(propylene carbonate) (PPC), the copolymerization product of carbon dioxide and propylene oxide, have been put into the stage of industrial production. However, since it has a glass transition temperature (Tg) of commonly 30° C.-40° C. and is amorphous, there are defects such as large brittleness at low temperature, poor dimensional stability at high temperature, and the like. It is difficult to be used as plastic alone, and is generally used as a modifier for rubber or plastic, which limits its wide development and application.
Chinese Patent Publication No. CN1176269 discloses a modification method of an aliphatic polycarbonate styrene-butadiene rubber. This modification method may not only provide a modified styrene-butadiene rubber having excellent thermal resistance and mechanical properties, but also this method employs inexpensive aliphatic polycarbonate modified styrene-butadiene rubber, and the aliphatic polycarbonate is synthesized by the copolymerization of carbon dioxide. The cost of the modified product is similar to that of a pure styrene-butadiene rubber. The wide use of aliphatic carbonate may not only develop new resources and alleviate shortage of chemical raw materials, but also has great significance for controlling the content of carbon dioxide in atmosphere, alleviating global green-house effect, and protecting ecological environment.
Chinese Patent Publication No. CN1436812A discloses a composite of a polyhydroxyalkanoate and a poly(propylene carbonate). This composite is obtained by premixing 100 parts by weight of one or more polyhydroxyalkanoates, 10-100 parts by weight of a poly(propylene carbonate), 10-100 parts by weight of a plasticizer, 1-3 parts by weight of an antioxidant, and 1-4 parts by weight of a nucleating agent and then mixing and pelletizing the mixture at the melting temperature of polyhydroxyalkanoates. This composite combines the advantages of a polyhydroxyalkanoate and a poly(propylene carbonate), improves the brittleness of the polyhydroxyalkanoate, and has good overall mechanical properties.